1. Field of the Invention
The present invention relates to a data recording apparatus for recording data on a record (recording, recordable or recorded) medium, a method therefor, a data reproducing apparatus for reproducing data recorded on a record medium, a method therefor and a recording medium on which data has been recorded. More particularly, the present invention relates to an information providing/collecting apparatus for providing and collecting so-called multimedia information, such as video information and music information, or program information and a method therefor.
2. Related Background Art
As a data record medium on which information signals, such as audio data, video data and various data items, are recorded, means for optically recording information signals, specifically, a so-called compact disk (CD) for use in the music field and a CD-ROM which meets the CD standard and which is used for data recordings are used all over the world in recent years.
Therefore, information providing service have been recognized as a so-called data base system and a personal computer communication system in each of which a user terminal (a terminal of an information collecting side) and an information provider are connected to each other through, for example, the telephone line to enable information required by the user to be taken out. Another information providing service has been recognized with which a large-capacity medium, such as a so-called CD-ROM having encoded information recorded thereon for distribution and key information for decoding encoded information is transmitted to the user by, for example, a communication system so that encoded information recorded on the CD-ROM can be decoded and decoded information can be copied on a hard disk or the like so as to be used.
Moreover, a technique has been disclosed in Japanese Patent Publication No. 2-60007 in which a password formed by encoding a file key by using a code key is supplied to a computer; and a program written on the record medium is decoded by a coding mechanism to prevent copying and sharing of the software program.
Therefore, all of the information items recorded on the foregoing CD or the CD-ROM are read by a reproducing apparatus and copied onto, for example, a hard disk. Then data copied onto the hard disk is supplied to an encoder system for the CD or the CD-ROM to newly make a CD or a CD-ROM so that a pirate edition can easily be manufactured. As described above, the security function, such as the copy protection, in the past have been unsatisfactory.
The foregoing problem is also critical for a so-called digital video disk (DVD), which is expected to be the data recording medium for a next generation.
On the other hand, in the conventional information providing service, a method has been employed in which key information for decoding is transmitted to a user by means of voice through a telephone line. Thus, key information has not been encoded particularly well. Further, the foregoing method has risks when keeping security is of concern.
In the case where communication is employed to transmit key information, one-to-one connection is usually established. Therefore, there is substantially no risk of key information being stolen. However, in the case where key information is transmitted through a network, there arises a problem in protecting key information.
Therefore, in an information providing system, in which mediums, on each of which encoded information has been recorded in a large quantity and are to be distributed by the information provider; and only in a case where a user requires information to obtain from the medium, key information for decoding the code is supplied and accounting is performed, the problem in view of security is when key information is transmitted resulting in a risk arising in that key information can be obtained by a person other than the subject user. In the foregoing case, the information providing system cannot be held secure. If whether or not the user is a formal user cannot be specified, there is a risk that account can be assigned to another person. Also in the foregoing case, the information providing system again cannot be held secured.
Thus, security improvement in transmitting key information from an information provider to a user and reliable specification of a user are important requirements.